Although this invention is applicable to the dispensing of very small and precise amounts of fluids to be used in conjunction with the dispensing of other fluids or quantities of energy, it has been found particularly useful in the environment of the delivery of very small drops of dye to enhance the effect of laser energy. Therefore, without limiting the applicability of the invention to "delivery of very small drops of dye to enhance the effect of laser energy", the invention will be described in such environment.
There are well known benefits from the use of surgical lasers in the medical field in the area of welding or closure of openings in tissue, for example, the coagulation of tissue to close an opening (ophthalmological vessel coagulation). There are also benefits from the use of a laser beam to ablate tissue to make an opening such as an incision or hole in tissue. The advantages of laser welding arise primarily from the avoidance of suture material which may distort the healing process and promote excessive scarring, a shorter operative time, a hemodynamically more perfect flow surface, etc.
It has been known in the medical field to use various dyes (also known as chromophores or materials which absorb light based upon their intrinsic optical junction properties) which absorb specific wavelengths of laser energy. These dyes could be materials which are naturally occurring, which are synthesized, etc.. Prior to the laser surgery, a line or painting of dye was laid down on the tissue where the cut or weld was to occur. The surgical laser was then activated and the energy therefrom was directed along the line or painting of dye. There were at least two problems with this method of operation. First, the line or painting laid down on the tissue was too wide for some applications and second, the time delay between the placing of the dye and the directing of the energy from the surgical laser allowed the dye to flow out over the tissue. This resulted in the laser energy being dispersed or spread-out from the intended line of tissue and requiring higher laser power to do the required surgery with a decrease in the accuracy of the work done by the laser energy.
It has also been known in the art of laser surgery and laser coagulation, that a CW beam of relatively low power of laser energy may be directed to the target tissue for relatively long periods of time and allow the thermal diffusion away from the impact site for the coagulation or welding effects. It is also known to provide a pulsed-type laser using very high peak pulse power to deliver the same total energy in pulsed form to produce coagulation. With the pulsed-type laser, the same total energy is delivered to the target tissue and coagulation only occurs at the impact site of the laser energy because there is not time for thermal diffusion to occur.
This invention effectively deals with these problems and allows greater accuracy in laser surgery with a laser of less power than was previously necessary for the same operation.